The mermaids of the Kastolatian Sea had been constantly at odds with the humans in the region. Believing a myth that mermaid flesh offered immortality, the fishermen hunted them relentlessly. However, a brief respite for the mermaids was obtained when Porkyus, leader of the mermaids, was given governance over the region in return for her loyalty to Empress Endora and the Empire. With the death of Prokyus, the region fell back into chaos until the White King Tristan ruled the continent and brought about an age of peace.

The Mermaid has the appearance of a blonde woman, with the upper body of a female and the lower body of a pink fish. She wields a trident in both hands. A class that excels in the water, the Mermaid can act either as a decent front row attacker or cast a magical blizzard on its enemies from the back row. At Level 11, with a Cha. of 50+, and an Ali. of 50+ the Mermaid can be promoted into a Nixie.

Of the only two classes well-suited for aquatic combat, the Mermaid is the better one. The Mermaid funcions as a physical, frontline fighter better suited for battles in water tiles; sadly, there are not many coastal maps in the game, and in land combat the Mermaid is rather lackluster.

The Mermaid has access to two exclusive skills. The first is Lullaby (Wind, 15 SP, RNG 6, AOE 1-5), which can inflic Sleep on enemies and increases AOE the higher the user's INT stat is. The second is Cheer (Wind; 22 SP, RNG 5, AOE 1), which increases an unit's AGI greatly. These skill give the Mermaid utility as a supporter whenever she isn't attacking, and Lullaby can be used for great effect against enemy crowds.

As mentioned above, the Mermaid has the rare "Snow-Trudging" movement type, which makes her better suited for winter maps if she's forced to fight landlocked.

Overall, the Mermaid is a decently balanced unit with good support options, but her lack of magic options, offensive skills, and dependancy on water tiles make her an easily overshadowed class. If players want to keep at least one Mermaid in their party, it's suggested to recruit Aerial instead, as she does a little better than generics and comes with matching element (Wind) for her skills.